This invention relates to carbon black manufacture. In one of its aspects this invention relates to carbon black reactors. In another of its aspects this invention relates to the supplying of feedstock to carbon black reactors. In still another aspect of the invention it relates to the production of carbon black having negative tint residual.
It has been disclosed in U.S. Pat. No. 4,071,496 that the incorporation of a carbon black with a low tint residual, preferably below minus 6, in a rubber composition causes the hysteresis or heat buildup of such a rubber composition to be significantly lower than that of a rubber composition incorporating a carbon black with a higher tint residual, while the abrasion resistance of such rubber compositions incorporating these different carbon blacks remains essentially unchanged. Great importance has, therefore, been placed upon the discovery of methods and apparatuses that are capable of producing a carbon black having low tint residual.
Tint residual is the difference between the measured tint and the tint calculated from the structure, nitrogen surface area and CTAB surface area of a carbon black sample in accordance with a specific formula. EQU TR=T-[56.0+1.057(CTAB)-0.002745(CTAB).sup.2 -0.2596(DBP)-0.201(N.sub.2 SA-CTAB)]
In this formula the abbreviations used have the following meanings and the properties are measured as described:
TR: This is tint residual. PA1 CTAB: This is the surface area of the carbon black measured in accordance with ASTM method D3765-80, m.sup.2 /gm. PA1 N.sub.2 SA: This is the surface area of the carbon black measured using nitrogen in accordance with the ASTM method D-3037-76, m.sup.2 /gm. PA1 Compressed DBP: This is the structure of the carbon black and is measured in accordance with ASTM 3493-76, cc/100 gm. This property is also referred to as 24M4 DBP. PA1 T: This is the tint or tinting strength of the carbon black measured relative to the industry reference black IRB No. 3 which has an arbitrary value of 100. Tint is measured in accordance with ASTM 3265-80.
The surface area, as described above as CTAB and N.sub.2 SA is usually an inverse measurement of the nodule size of the carbon black. The structure of the carbon black, expressed above as DBP, is a measure of the complexity of the individual carbon black aggregates or of the number of nodules "fused" together in one carbon black aggregate.
It is therefore an object of this invention to provide method and apparatus by which low tint residual carbon black can be manufactured. It is another object of this invention to provide a feedstock nozzle that is useful in a carbon black reactor for the production of carbon black having a low tint residual.
Other aspects, objects, and the various advantages of this invention will become apparent upon reading the specification and the claims and studying the appended drawing.